"Big classes can hide too much. This question comes up over and over again from people new to unit testing: "How do I test private methods?" Many people spend a lot of time trying to figure out how to get around this problem, but, as I mentioned in an earlier chapter, the real answer is that if you have the urge to test a private method, the method shouldn't be private; if making the method public bothers you, chances are, it is because it is part of a separate responsibility. It should be on another class."